Guide to Buying the Right Size Battery
Purchasing the proper sized battery for your application can be intimidating. Too small, and you find yourself running out of juice too soon. Too big, and you may be spending extra money when you didn’t have to. To understand calculating our perfect battery size, we must first learn a few basic definitions.
Volt or Voltage (V):
Voltage is the pressure from a power source that is pushing electrons through a loop, enabling them to do work such as power a trolling motor or turn on a light bulb. Batteries are marked with a nominal voltage that is fixed (such as 12, 24, 36, or 48 volts). On the other hand, electronic devices will always operate when receiving a fixed voltage. For example, a 12-volt device needs a battery that supplies 12 volts to operate.
Current – Ampere (A):
If voltage is the pressure, current is the flow rate. An ampere, or amp, is the international unit used for measuring current. Amp’s measure how much electricity “flows” per second. As the rate of current goes up, the measure of amps will also go up. An electronic device usually works on a fixed voltage, but the number of amps it draws can vary. One example is a dimmer light switch, as you slowly raise the dimmer switch you are slowly increasing the amps being sent to the light bulb. The voltage does not change, but the increase in amps will increase the brightness of the light bulb. The same holds true with operating a trolling motor.
Example: I have a 55 lb trolling motor running on speed setting 4. The trolling engine runs on 12V and draws 15A at that speed. If I increase to speed setting 8. The motor still runs on 12V but now pulls 30A. The voltage remains the same but the number of amps increased.
Power – Watts (W):
Power is volts multiplied by amps, or W = V x A. Power is generally measured in watts (W). This is the amount of energy consumed by a device and therefore an indication of how powerful it is.
Example: I have a 12V trolling motor that draws 30 amps. The power consumption is 12 x 30 = 360W.
It is important to note that power can change on the same device if the amps are increased.
Example: I have a 24V trolling motor that I am running on speed setting 3. The motor runs on 24V and draws 10A. This would give it a power consumption of 240W (24 x 10 = 240). If I increase my speed setting to 5, the motor now draws 15A, but still runs on 24V. The power consumption of the trolling motor is now 360W (24 x 15 = 360).
Capacity – Amp hours (Ah):
Amp hours, or Ah, is a measurement of battery capacity. The Ah rating of a battery tells us how many amps the battery can deliver in one hour. Higher Ah rating means more runtime. As an example, a 12V lithium battery with a capacity of 100Ah can deliver 100Ah to a 12-volt device for one hour. This also means that the same 100Ah battery could operate a 12V device for 4 hours if the amp draw was 25 amps ( 100 ÷ 25 = 4 ). When measuring capacity, we see two values: rated capacity and usable capacity. When shopping for batteries, it is important to understand lithium batteries have a significantly higher proportion of usable capacity than lead acid batteries. For more information about the differences between these two battery types, check out this article.
Example: I run my 55 lb trolling motor at speed setting 4, drawing 15A at 12V. I have a 12-volt battery of 100 Ah. My total run time is now 6.7 hours ( 100 ÷ 15 = 6.7 ). When I switch to speed setting 8 the motor draws 30A. My total runtime is now 3.3 hours ( 100 ÷ 30 = 3.3 ).
Capacity – Watt-hour (Wh):
Another commonly used terms to measure battery capacity is Watt-hour, or Wh. Wh is calculated by multiplying battery voltage and amp hours. For example, a 12v 54Ah battery would have 648Wh ( 12 × 54 = 648 ). A 36v 100Ah battery has 3600Wh ( 36 × 100 = 3600 ).
Battery Size Calculator
Step 1: Determine your battery voltage. Is your application 12V, 24V, or 36V?
Step 2: What is your device’s max intended amp draw?
Step 3: What is your target operating time for this battery at max amp draw?
Use the calculator below to help determine the proper Ah rating you will need from your battery.
Battery Ah Rating Required :
0ah battery size
Each battery has built in PCM protection board from Over-discharge, Over-charge, Short Circuit etc….
LiFePO4 battery is Environmentally friendly, which will not destroy the ecological environment, also have no memory effects.
Have low internal resistance and high flat voltage characteristics during strong current discharge, which ensures a wider application field.
Provide long storage life with few limiting conditions. It offers problem-free charge after long storage, permitting to use in a wide range of applications.
|Part Number||LiFePO4 12V 100Ah Rechargeable Car Battery|
|Max Charge Voltage||14.6V|
|Discharge Cut Off Voltage||10V|
|Max. Continuous Discharging Current||500A|
|Cycle Life||≥2000 cycles|
|Dimensions (TWH)||318175190mm ±5mm / Customized|
|Encapsulation||Customized is available|
|Operating Temperature||Charging: 0~45℃/Discharging:-20 ~60℃|
|Storage Temperature||-10 ~ 45℃|
|Humidity||5% to 95% relative humidity|
|Main protection function||Overcharge, over discharge, over current, short circuit, etc.|
|Delivery period||7-20 days, depending on stock and quantity.|
|1) Car, Automobile, Auto|
Generally, what are Lithium-Ion Batteries? A. Lithium-ion batteries are rechargeable batteries in which lithium ions move from the anode to the cathode during discharging and back when charging. They are popular batteries for use in consumer electronics because they provide high energy density, possess no memory effect and have a slow loss of charge when not in use. These batteries come in a wide variety of shapes and sizes. Compared to lead-acid batteries, Lithium-ion batteries are lighter and provide a higher open circuit voltage, which allows for power transfer at lower currents. These batteries have the following characteristics:
Features of ionic Lithium-ion Deep Cycle Batteries:
Light weight, up to 80% less than a conventional, comparable energy storage lead-acid battery. Lasts 300-400% longer than lead-acid. Lower shelf discharge rate (2% vs. 5-8% /month). Drop-in replacement for your OEM battery. Expected 8-10 years of battery life. No explosive gasses during charging, no acid spills. Environmentally friendly, no lead or heavy metals. Safe to operate! The term “Lithium-ion” battery is a general term. There are many different chemistries for Lithium-Ion batteries including LiCoO2 (cylindrical cell), LiPo, and LiFePO4 (cylindrical/prismatic cell). Ionic mostly focuses on designing, manufacturing and marketing LiFePO4 batteries for its starter and deep cycle batteries.
What are LiFePO4 (Lithium Iron Phosphate) Batteries? A. Lithium Iron Phosphate (LiFePO4) batteries provide several advantages over traditional Lithium-ion batteries based on LiCoO2 chemistry. LiFePO4 batteries provide much higher specific capacity, superior thermal and chemical stability, enhance safety, improve cost performance, enhanced charge and discharge rates, enhanced cycle life and come in a compact, lightweight package. LiFePO4 batteries an offer a cycle life of over 2,000 charge cycles!
Why should I get a ionic’s lithium-ion “Deep Cycle” energy storage battery? A. Lithium-ion batteries provide multiple advantages over standard lead-acid batteries for energy storage use that we’ll outline below:
Substantially Lighter – Lithium-ion batteries are just a fraction of the weight of the original lead-acid battery. Powerful – Lithium-ion batteries operate at a higher voltage than standard lead-acid batteries, giving you faster engine speed for longer durations. Lead-acid batteries drop to just 12.5V when only 20% of the battery capacity is used, but lithium-ion batteries provide over 12.8V even when only 20% of the battery capacity is left. Low Self-Discharge Rate– Lead-acid batteries lose 4%-25% of their charge every month depending on the quality of the plates and separators used. If you leave a vehicle unattended for a month, the lead-acid battery might lose too much power and the vehicle might not start. On the other hand, our lithium battery chemistry loses less than 3% of charge per month; you can go for several months without having to worry. Environmental Friendly– Ionic batteries contain no toxic substances. There is no poisonous lead or corrosive sulfuric acid and as a result, no possible way for an explosive gassing event that is common with lead-acid batteries. In addition, there is no need to maintain acid levels or worry about venting like traditional lead-acid batteries do. The only maintenance that ionic batteries require is ensuring that the battery never drains beyond 80% to ensure optimal life. Long Lasting– Cheap lead-acid batteries usually only last 1 to 2 years while gel and AGM lead-acid batteries last 3-5 years with proper maintenance. However, ionic’s lithium-ion batteries can provide 8-10 years of use, easily exceeding the life of any lead-acid battery. Battery life depends purely on proper operation and maintenance, so use common-sense and ensure the battery does not drain beyond 80% discharge. If you are replacing a lead-acid battery in two years or less due to deep cycling damage, you will save money in the long run moving to a ionic lithium-ion Fast Recharging – ionic’s lithium-ion batteries can accept charge current at up to 5 times faster than a lead-acid battery. What’s more, the charge efficiency is about 75% for lead-acid in contrast to 97% for ionic’s lithium-ion battery. That means less energy is needed to charge and causes less strain on your alternator.
What advantages does ionic “Deep Cycle Batteries” have over other batteries? A. ionic utilizes the latest advancements in lithium-ion battery technology along with custom features to provide you with the best battery for your vehicle:
Internal Cell Balancing Circuit – ionic batteries have a micro-processor controlled internal cell balancing board in each of its batteries designed to maximize the performance of each cell in the batteries. Battery Management System (BMS) – ionic lithium-ion Smart batteries contain a solid state switch that controls temperature volatility. This switch prevents overcharging and discharging, improving the overall lifespan performance and safety of the batteries. Quality Engineering – ionic’s innovation laboratory prides itself on the design and construction of its batteries utilizing the highest quality components in all phases of design and construction. The ionic built-in intelligent components guarantee the safety and quality of each ionic product. Prismatic Cells – Cylindrical cells only come in certain sizes which limits the possible shapes and sizes of the starter battery case designs. As such, batteries fit for many vehicles may be poor, or impossible as they are too wide or too tall and create internal hot spots. Ionic prismatic cells on the other hand, are rectangular packages which can be freely designed and sized according to the size requirements of the battery case. As such, ionic offers perfect drop-in fit in most vehicles along with having better thermal management properties.
How does ionic’s “Deep Cycle” capacity (Ah) rating compare to lead-acid Ah ratings? A. Ionic’s “Deep Cycle” batteries have true lithium capacity rating at 1C discharge rate meaning a 12Ah “Deep Cycle” lithium-ion battery will be able to provide 12A for 1 hour. On the other hand, most lead-acid batteries have a 20hr or 25hr rating printed for its Ah capacity meaning the same 12Ah lead-acid battery discharging in 1 hour would typically only provide 6Ah of useable energy. Going below 50% DOD will damage a lead-acid battery, even if they claim to be a deep discharge battery. Thus a 12Ah lithium battery would perform closer to a 48Ah lead-acid battery rating for higher discharge currents and life performance. Ionic’s lithium-ion batteries have 1/3 the internal resistance of a similar capacity lead-acid battery and they can be safely discharged to 90% DOD. Lead-acid internal resistance rises as they are discharged; the actual capacity which can be used may be as little as 20% of the mfg. rating. Discharging in excess will damage the lead-acid battery. Ionic’s lithium-ion batteries hold a higher voltage during discharge.
V 100Ah LiFePO4 Lithium Iron Phosphate Battery
SKU: DBT-LFP12100-1C01-US UPC: 810081401081 Availability: Please allow up to 1 to 2 business days for processing. Shipping may take up to 4 to 6 business days. Width: 13.07 (in) Height: 8.66 (in) Depth: 6.77 (in)
Bulk discount rates
Below are the available bulk discount rates for each individual item when you purchase a certain amount
- Buy 4. 7 and get 5.00 off
- Buy 8. 11 and get 10.00 off
- Buy 12 or above and get 15.00 off
Add to Wishlist
Dr. Prepare LiFePO4 Battery stores much more power compared with other Lead Acid batteries, with only 1/3 of the weight and size. The integrated Battery Management System (BMS) protects the battery from various abnormal conditions, so that the battery cells have a long cycle life and exceptional discharge performance.
If you’re searching for a deep cycle battery for RV, marine, or off-grid applications, then this lithium-ion battery is the perfect solution for you!
- 【Deep Cycle Lithium Battery】 Premium and state-of-the-art Lithium Iron Phosphate battery cells provides 1000 cycles, which is 2-3 times to Lead Acid Battery with 300~500 cycles. It can reach up to 2000 cycles when the discharge rate is lower to 0.1C~0.2C (10～20A). can It can help you save money without multiple purchases. Due to its low self-discharge rate, the LiFePO4 battery will be fully ready for operation even after a year of storage. Without memory effect, no matter what state the battery is, it can be used as soon as it is charged.
- 【Extendible Widely Use】 To get more capacity and higher voltage, the auto-balancing feature ensures batteries to be connected in parallel safely, without internal state non-uniformity issues. Support to connect a 1200W converter to power tower fans, lights, camera, TV and so on. 12V deep cycle lithium-ion battery widely use in most areas such as RV, camper, marine, power backup, off-grid applications, other SLA / AGM batteries replacement, etc.
- 【Built-in BMS Protection】 Dr. Prepare 100Ah LiFePO4 battery has built-in battery management system (BMS) to monitor the battery temperature. If the LFP battery exceeds 140℉ (60℃), the battery will be at risk of high temperature, which may bring sparks. Our LFP battery has built-in high temperature detection sensor inside the aluminum heat dissipation plate, to prevent the battery from overheting and ensure to work in a safe range. The BMS also can prevent the battery from short circuit, overcharge, overdischarge, overcurrent, overvoltage, low voltage and so on.
- Please notice that our battery doesn’t have low-temperature protection! Low-temperature protection is that under the monitoring of BMS temperature sensor, the battery will stop charging during 23~32℉(-5~0℃) and stop discharging during.4~23℉ (-20~-5℃). The battery will reach.4℉(-20℃) only when the outdoor temperature is lower to.40~-22℉ (-40~-30℃), which means the function of low-temperature protection is not essential in actual use. And our lithium battery can be used in an emergency at extremely low temperatures.
- 【Environmentally Friendly】 Dr. Prepare Lithium battery is only about a 1/3 of the weight of lead-acid battery in the same capacity, and it is equipped with a fabric handle, which make it easy to carry and use it anywhere outdoor. Our LifePO4 battery is made from non-toxic materials which makes it completely safe to the environment.
- 【High Efficiency Battery 】Our 12V 100Ah lithium battery provide quick charge and discharge by 1C. LiFePO4 battery compatible with solar panels (not included) as well to get recharged gradually in sunlight. It can work efficiently in a wide range of temperature while maintaining high capacity.
- 【Best Service】The batteries will be shipped from California, USA. We provide 3-year battery warranty and lifetime technical support, if you have any questions, please feel free to contact us.
Due to the low self-discharge rate, a fully charged LiFePO4 battery can potentially hold a charge up to 1 year.
Batteries to be connected have the same capacity.
Connecting batteries of the same brands is recommended.
Fully charge the batteries before parallel connection.
Compatible with 1000W solar panels (not included) to get recharged gradually in direct sunlight.
1 x Lithium Iron Phosphate Battery1 x User Manual
|Cell type: lithium iron phosphate (LiFePO4)||Max. charging voltage: 14.6V|
|Rated capacity: 100Ah (1280Wh)||Max. discharging current: 100A|
|Rated voltage: 12.8V||Max. charging current: 50A|
|LED screen: No||Charging temperature range: 32°F~113°F / 0°C~45°C|
|Cycle life: 1000 cycles||Discharging temperature range: 14°F~140°F /.10°C~60°C|
|Net weight: 25.11 lb / 11.39 kg||Battery box: ABS plastic|
|Storage temperature range:.4°F~113°F /.20°C~45°C (store for 1-3 months);.4°F~68°F /.20°C~20°C (store for 1 year)|
|Size (L x H x W): 13.07 x 8.66 x 6.77 inch / 332 x 220 x 172 mm|
Please read through all the labels on the battery and this user guide before the first use.
Keep the battery away from rain, splashes, and any wet locations.
DO NOT short circuit the battery.
DO NOT string batteries in series.
DO NOT reverse connection polarity wiring.
DO NOT expose the battery to fire, heat sources, wet locations, or direct sunlight.
DO NOT open, dismantle, or modify the battery.
DO NOT drop, crush, shake, strike, or penetrate the battery.
Please use the specified charger to charge batteries.
Fully charge your batteries separately before parallel connection.
Low-temperature protection is that under the monitoring of BMS temperature sensor, the battery will stop charging during 23~32℉(-5~0℃) and stop discharging during.4~23℉ (-20~-5℃). The battery will reach.4℉(-20℃) only when the outdoor temperature is lower to.40~-22℉ (-40~-30℃), which means the function of low-temperature protection is not essential in actual use.
No, the charger is not included. You can either prefer a 12V trickle charger (AC to DC) or solar panels with a 12V controller (DC to DC) configured for a LiFePO4 battery. The maximum charge current is 50A.
You can connect our 12V 100Ah LiFePO4 battery to your DC 12V appliances. For appliances rated at AC 110V, we advise you to connect our 12V LiFePO4 battery with a 12V Max. 1200W inverter to run AC appliances.
Calculating How Big Your Battery Needs To Be
If you have a Camper trailer, Caravan or other RV and you like to spend time away from a 240 volt power source, this article will give you some answers that the sales people avoid. It will allow you to estimate the size and number of batteries that will suit your camping.
As always there is a little explanation required to ensure that we are at the same starting point. The aim is not to make it complicated, but to explain it so it makes sense.
A blank calculation sheet can be downloaded from the end of this article, however we recommend you spend a few minutes reading why and how it works.
How will we measure power?
The amount of electricity used to run a device or appliance may be defined as watts or as amps. If you know one you can calculate the other, provided you know the voltage.
We want to deal in Amps, as that is how the Deep Cycle batteries are rated. It is widely accepted at this stage that Deep Cycle batteries are the best option for RV use. In the past we recommended the AGM style (Absorbed Glass Mat) as the best for any Recreational Vehicle, but in more recent times as Lithium Batteries have become more affordable we believe the benefit is worth the initial setup costs. If you are looking for a battery for a new setup or needing to replace an existing Deep Cycle battery take a look at our related article.
Lithium vs AGM Batteries
An in-depth look at the advantages of Lithium Batteries over the long time favourite AGM for Caravan Camping applications.
A 100ah battery should provide 1 amp for 100 hours, 2 amps for 50 hours, 3 amps for 33 hours etc. It would be nice if this equation held true all the way up to 100 amps for 1 hour, but there are some limits to the maximum rate of current draw, and how much of that 100amps you can actually use without destroying your battery. We will get to those after you understand a few more things, but for now we want to know how many amps stuff uses.
Below: A simple example, but heavy user of power is a 12 volt hair dryer rated at 10 amps. A 100 ah battery should give you (100/10=10) 10 hours of usage.
If you use it for 5 mins a day, it could last 120 days. Happy wife, happy life.
If a device specification does not include amps but does include watts, the formula you need is:
Watts / Volts = Amps per hour
Below: An example where we need to calculate the amps. A very small user of power is a 1.2 watt LED light running on a 12 volt power source will use 1.2W / 12V = 0.1 amps. Therefore a 100ah (amp hour) battery will last for 1000 hours.
A slightly different example is a 60 watt fridge running on a 12 volt power source uses 60 /12 = 5 amps, but only while the motor runs.
60 watt fridge. divided by. 12 volt battery. uses 5 amps of electricity (when running)
But. the fridge motor does not need to run all the time, in fact this model indicates it only needs to run about 15% of the time. 5 amps by 15% = 0.75ah/h. This fridge can operate over a period of 133 hours, or 5.5 days if the guidelines are meet.
Guidelines may be exceeded or not reached. For example this chest fridge used at Thredbo in winter may last 300 hours, but in Darwin in summer only 72 hours if you keep exchanging the beer!
How many Amp Hours do you really get from a 100ah battery?
Amp Hours (ah) is the rating used by Deep Cycle battery manufacturers as a way to compare batteries, but we cannot just measure how many Amp Hours are left in a battery. We can use a voltmeter to get the voltage, and this can be used to get a good approximation. You need to know a few things first.
1) Low voltage cut off
First, you cannot use 100% of a battery for anything useful. To understand this, look at the following chart comparing a conventional Wet Cell battery and an AGM battery where the voltage reading shows approximate charge left.
Figure 1: Voltage indicating charge left.
If you have a 12V battery system, then one of the most useful items you can have is a Voltmeter. An effective one we sell is shown below. It plugs into a cigarette lighter socket and shows the voltage of your batteries. If you already have a multimeter it will also work.
Projecta. Digital 12/24V voltmeter
When you have finished charging your battery you may get a reading well over 13 volts, however this will be a surface charge and will settle to a real reading of around 13 volts in an AGM battery or 12.6 volts in a Wet Cell battery. If you have a small load on your battery, say a couple of lights, the reading you get from your voltmeter when compared to the table or chart above, will show approximately the remaining battery charge. A moderate or heavy load will give a distorted reading until the batteries have rested and the charge equalises.
Looking at Figure 1 above you will notice that 12.1 volts AGM, or 12.1 volts for Wet Cell indicates you have used 50% of the capacity of the battery, you should have 50% remaining.
However, once you get to around 30% remaining the voltage will not be sufficient for most appliances, you may get a light to work but your water pump will not work very well. Using a battery below these levels will also severely reduce the number of recharge cycles you get from your battery.
Battery chargers like the SETEC (there are others) control the current draw from the battery as well as charging the batteries. These will prevent you drawing current from the batteries once the voltage drops below the ideal minimum level.
Most battery manufacturers indicate you will get the longest life from a battery by only discharging to 50%. This maybe the ideal case, but in an RV when you have to buy an extra battery, find storage space and pay for vehicle fuel to cart extra batteries that weigh about 30kgs each, I believe it is not unrealistic to allow for discharging to 40% or even 30% on those longer stays or when your other charging options don’t work out. Yes, you may need to replace your battery a year earlier, but you have made savings along the way. Just one night away from a caravan park will save 30 plus extra weight for ever kilometre you travel.
Again it is important to note that the voltage shown will only be accurate if there is at least some load, but definitely not a load exceeding 5% of the batteries capacity. If the battery has just been charged or heavily discharged, it must be given time to equalise before taking a reading.
Using a water example, imagine 6 tanks of water (like 6 cells in a battery) each joined together with a straw. If you fill one end tank using a garden hose or drain the other end using a garden hose it will take some time for all tanks (or cells) to be at equal levels.
The time it takes to equalise is something you will get used to, you certainly don’t panic if your voltage drops down while you use the microwave for a couple of minutes (inverters can consume quite a bit of power while in use). A low load that is drawing power no faster than the battery can equalise will give a reasonable value for the Charge remaining, by reading the voltage.
Be aware also, that a battery under no load at all may still show 12V, but have little or no amp hours left.
There are a few advanced gauges that will calculate your capacity based on actual recent usage, but the cost is still beyond most recreational users. They are more like a mini computer taking and recording sample data and making predictions of capacity remaining and how long it will last if you continue to use it at the present rate. See Below:
What size solar panel to charge 100ah battery is determined by the wattage of the solar panel you need to buy
If you have a 12 volt 100ah battery and you buy a 300w solar panel, it will take you 4 hours to fully charge the battery, you can calculate this using the following formula
W (watts)/V (volts) = A (amps)
We can calculate from the formula 300/12=25A which means that the output current of this panel is 25A
Then we can calculate how long a 12 volt 100ah battery can be fully charged
According to the formula 100AH/25A=4H which means that to fully charge a 12 volt 100ah. It would take 4 hours to fully charge
If you have a 24V 100ah battery, it will take 8 hours of work for your 300w solar panel to fully charge this battery.
In fact, the actual charging time is still longer than this, this only means that the solar panel is always working at 300W, you also need to consider the household light environment, suppose your home receives 6h or less of light per day, then your charging time will require two or more solar panels or higher efficiency to charge your battery, of course it is best to have a controller to to adapt the power supply for charging.
Nowadays, solar panels can also work at night, but their efficiency is very low compared to the sunlight during the day, so if possible, you can place different solar panels at different locations in your home to ensure that the whole home or the whole power system works.
If you have a 12 volt 100ah battery and you buy a 300w solar panel, it will only take you 4 hours to fully charge it.